"For a example, a machine with a duty cycle rating of 150 amps at 60 percent duty cycle means that the machine can produce 150 amps for six minutes and then must cool for four minutes. A machine with a rating of 300 amps at 100 percent duty cycle means that the machine can produce 300 amps of current continuously."

Tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTAW)
is a process were joining of two metals occur. Heat from an electric arc formed
between a tungsten electrode and the metal being worked on melts the ends of
the metal and the probe so welding may occur. A chemically inert gas or a mixture
of inert gases, such as argon, helium or hydrogen, is used to shield the metal
from oxidation.

Different factors are taken into consideration when selecting the amount of current
that will be used, thus the quantity of electric current that flows through a
TIG welder varies. The type and thickness of the metal to be welded determines
the amount and type of current, which in turn determines the type of shield gas
to be used. Direct current (DC) with the electrode negative offers deep penetration
and fast welding speed, with helium gas used as a shield resulting in a large
amount of current being used. Direct current with a positive electrode offers
less penetration but removes surface oxides from metals resulting in lower amounts
of current being used. Alternating current (AC) removes oxides from metal surfaces
with a sputtering motion allowing for excellent welds resulting in a moderate
amount of current being used. Argon though must be used as the shielding gas
with AC instead of helium because helium doesn't sputter. Argon is the most commonly
used shielding gas regardless of direct or alternating current.

The electrode diameter as well as its composition of tungsten will affect the
amount and type of current flowing through the TIG welder. Electrodes small in
diameter with a majority of its composition made from tungsten may carry only
small amounts of current regardless of its polarity. Electrodes large in diameter
despite composition and polarity will carry large amounts of current through
the welder.

Manufacturers make products such as automobiles, home appliances, and furniture
by using TIG welding. Construction companies use welding techniques to build
various structures such as bridges and edifices. The amount of current varies
with numerous factors. This results in a large variation of electric current
flowing through a TIG welder. The range of current starts as low as 5 A and goes
as high as 1000A.